Chemical Science. 183 



cause the effect, but the moment a little lime is added it happens at 

 once. Milk with twice its bulk of water is not coagulated by sul- 

 phuric acid cold, but apply heat and the effect is produced, because 

 a little phosphate of lime in the milk then becomes sulphate, and 

 acts as above. Generally, the combinations of cheesy matter with 

 acids are irnputrescent. Well washed sulphate of caseum was left 

 with water for a long time : it gradually disappeared, but produced 

 no putrid odour. 



Vegetable acids precipitate caseum, unless in excess. Potash, 

 soda, and ammonia produce very soluble compounds with it, which 

 are perfectly transparent, unalterable by air, and resemble gum. 

 All earthy bases and metallic oxides form insoluble compounds. All 

 salts, except those with base of potash, soda, or ammonia, combine 

 with caseum to form insoluble compounds. Even a little selenitic 

 water put into a solution of caseum, though it causes no change at 

 first, yet, when heat is applied, produces insoluble pellicles, which 

 are a compound of the caseum and earthy salt. The same or still 

 more striking coagulation happens with sulphate of magnesia and 

 acetate of lime. 



Strong alcohol does not affect caseum ; weak alcohol dissolves it. 

 Sugar renders a solution of caseum more liquid : gum arabic renders 

 it quite insoluble, probably from the presence of earthy salts in it. 

 Infusion of galls acts with it as with gelatine. M. Braconnot sus- 

 pects that vegetable albumen is nothing more than caseum with 

 some earthy salts present. 



Improved Milk. Besides caseum and butter, milk contains salts, 

 &c. which are not particularly desirable. M. Braconnot took 2J litres 

 (4.4 pints) of milk, heated it to 113 F., gradually added dilute muri- 

 atic acid, and agitated the whole. The curd formed contained the 

 caseum and butter, and, being separated from the whey, was gradu- 

 ally mixed with 5 grammes (77 grains) of crystallized sub-carbonate 

 of soda, reduced to powder and warmed. No water was added, 

 but the whole gradually dissolved. It had the weak acidity of recent 

 milk, and formed about a half-litre of cream (a fifth of the first bulk), 

 capable of numerous applications in domestic economy. If made 

 up to its first bulk with water and a little sugar, it forms a milk 

 more agreeable than the original; or it may be flavoured, &c., and 

 used as cream. If it be heated with about its weight of sugar, it 

 becomes remarkably fluid, and forms a perfectly homogeneous syrup 

 of milk, which will keep for any length of time, and which, by the 

 mere addition of a sufficient quantity of water, forms a perfectly 

 homogeneous white opaque liquid, which is in every respect like 

 sugared milk of improved flavour. The syrup diluted with water 

 forms a nourishing drink for invalids. Carefully evaporated, but not 

 beyond a certain limit, or the butter would separate, it gave, when 

 cold, a soft confection, which left for a twelvemonth in a loosely 

 stopped bottle, underwent no change. This, when exposed in thin 

 portions to the air, was rendered quite dry, and could then be crushed 



